You may be able to work around the problem by using nvidia-settings to save the EDID to a file, editing the mode in question to double the vertical timings, and then feeding it back to the driver with the CustomEdid option. I haven't tried that particular approach so I don't know if it'll work. Other than that, I don't think there's a workaround for this problem.

FWIW, Given the volume of CORRECT data that comes back from the TV via EDID, I think it's a monster screwup to have it broken so badly under linux. Under windows, it's perfectly fine.... So I have hope...

The xrandr issue that you cite may be the key to reproducing this for nVidia.

Many of us here are using this with MythTV, and we have X starting in a different mode (720p or something like that) and then only use 1080i when playing back 1080i material. What you're saying is that you can get 1080i working, but only if it's the starting resolution.

BTW: I've used that exact same modeline previously with no luck--just a black screen (not the messed up screen that I get with EDID values).

The xrandr issue that you cite may be the key to reproducing this for nVidia.

Many of us here are using this with MythTV, and we have X starting in a different mode (720p or something like that) and then only use 1080i when playing back 1080i material. What you're saying is that you can get 1080i working, but only if it's the starting resolution.

BTW: I've used that exact same modeline previously with no luck--just a black screen (not the messed up screen that I get with EDID values).

Since I upgraded from a Geforce 7 to a Gerforce 8 (driver 100.14.19) my modeline for a sanyo plv-z2 beamer doesnt work properly anymore, the mode gets validated with edid ignored and some other validation skips but the resulting output is much too small and the beamer cant recognize it as 720p anymore.
(the same xorg.conf works great with the geforce 7 and the older driver)

Dunno if that fits into this thread or if my problem goes even further (as i have edid disabled)

I should specify that the computer is connected via HDMI (it is a 7050-based motherboard). And the mode in question is one of the EDID modes sent by the TV. Custom modelines with doubled vertical timings do not work for me. The TV fails to sync to these modes.